Error when granting user 'Role' access to Kanban board

Issue Summary

Error when granting user 'Role' access to Kanban board

Not reproducible in the Support in-house environment

Customer reported this issue where they are seeing Error (such as Error 18522) when granting Role access to a specific Kanban board. The error is happening when editing user Role access permission in the specific Kanban Board slide > Manage Users tab. Below is the provided sequence but Support has not been able to reproduce this in-house. In customer's environment, this error currently is reproducible in only one Kanban Board ID=29.

User cannot edit persmissions on a Kanban board due to the error. The following are the sequence causing the error:
1) User goes to Kanban board
2) User chooses person and type of access they want for the other user
3) User chooses action from dropdown
4) User clicks save and gets the error

Steps to Reproduce

Support is unable to replicate this but the following are the steps in the customer environment:

• Open the specific Kanban board (ID=29)
• Go to the 'Manage Users' tab
• Attempt to update user 'Role' access from the 'Role' drop-down
• Save which is when the error occurs

Expected Results

There should be no error and role access update should work.

Actual Results

Currently not able to edit kanban board user Role access in the specific kanban board due to the error.

In Splunk, we have these logs, below:

 error_description: Failed to convert parameter value from a String to a Int32.

As from 2 separate HAR analysis, it seems every time the error is reproducible, the error number shown is different:

One Har shows the Response as 'Error #20971'
Another Har shows Response as 'Error #20999'

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available